Europhys. Lett.
Volume 76, Number 5, December 2006
Page(s) 965 - 971
Section Interdisciplinary physics and related areas of science and technology
Published online 03 November 2006
Europhys. Lett., 76 (5), pp. 965-971 (2006)
DOI: 10.1209/epl/i2006-10338-7

Internal pressure fluctuations in coacervates and syneresis

B. Mohanty and H. B. Bohidar

Polymer and Biophysics Laboratory, School of Physical Sciences Jawaharlal Nehru University - New Delhi-110067, India

received 13 April 2006; accepted in final form 5 October 2006
published online 3 November 2006

Syneresis exhibited by a heterogeneous polyampholyte coacervate (polymer-rich phase) is discussed through non-equilibrium statistical thermodynamics. It has been shown that the coacervate phase is associated with fluctuating excess internal pressure that gives rise to syneresis. It is proposed that energy is dissipated to the environment only by the surface of coacervate, whereas in the bulk, gelatin chains only exchange energy with each other with negligible or no dissipation. Consequently, the internal pressure inside the coacervate follows a damped oscillatory behaviour that relaxes slowly with time, independently of amplitude. We connect the volume of the supernatant released with time (exponential relaxation behavior) with the presence of long-lived nonlinear localized modes (the existence of breathers).

82.70.-y - Disperse systems; complex fluids.
64.70.Ja - Liquid-liquid transitions.
64.75.+g - Solubility, segregation, and mixing; phase separation.

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